Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in CPP):

Solution:
#include<iostream>
#include<queue>
#define INF 100000000
using namespace std;
int h,w;
int d[51][51];
string s[51];
void search(int x,int y,int cnt){
  if(x<0||y<0||x>=h||y>=w) return;
  if(d[x][y]<=cnt) return;
  if(s[x][y]=='#')return;
  d[x][y]=cnt;
  cnt++;
  search(x,y+1,cnt);
  search(x,y-1,cnt);
  search(x+1,y,cnt);
  search(x-1,y,cnt);
}
int main(){
  int cnt=0;
  cin >> h >> w;
  fill(d[0],d[51],INF);
  for(int i=0;i<h;i++){
    cin >> s[i];
    for(int j=0;j<s[i].size();j++){
      if(s[i][j]=='.') cnt++;
    }
  }
  search(0,0,1);
  if(d[h-1][w-1]==INF)cout <<"-1\n";
  else cout << cnt - d[h-1][w-1]<<endl;
}